A simple method to estimate the significance level of the catch probability in the catch removal method in river fish populations

This work presents a method for estimating the significance level of the capture probability when the capture removal method is used in riverine fish populations. The method is based on adjustment of the linear relationship between capture probability and an index of capture efficacy. With this method the population size, the statistic χ2 and the significance level of the capture probability can be estimated. This is a simple technique which can be applied in the field at the time of sampling. It does not require the use of computers and can determine in situ whether the catch is valid to calculate the population density.